The near universal adoption of Internet protocol (IP) as a standard for digital transmission is revolutionizing the traditional way of video delivery. Typical applications such as IPTV and live video streaming have become increasingly popular over the Internet. To efficiently utilize the bandwidth resources of the network in these applications, the video is usually compressed with suitable media coding schemes and then delivered only to subscribers who request it. For data delivery, multicast is considered the most efficient paradigm for such applications, but the scalability issue of traditional IP multicast hinders the deployment of a large-scale video delivery system with numerous channels.
IP delivery is also contemplated in virtual reality environments or applications that allow for virtual media viewing areas, including ones with multiple virtual TVs or screens. Mixed reality environments allow for virtual televisions to be displayed instead of (or alongside with) real televisions in a real environment. Virtual reality requires extremely high bitrates because the true “screen” is much closer to a viewer's eye than for an actual television ten feet away. Lower bitrates in a virtual environment cause a “screen door” effect, in which individual pixels are visible even if they would not be ten feet away.
It should be appreciated that a major challenge for existing virtual reality systems is combining realistic images with low-latency rendering, so that user's virtual reality experience matches the rapid feedback to movement observed in real environments. Existing systems often have long latency to measure changes in the user's position and orientation, and to rerender the virtual world based on these changes. 3D rendering is a complex and processor intensive operation that can take potentially hundreds of milliseconds. The result is that users perceive noticeable lag between their movements and the rendering of updated virtual environments on their displays. Three technology trends are compounding this challenge: (a) The complexity of 3D models is growing as more 3D data is captured and generated; (b) Resolution of virtual reality displays is increasing, requiring more computational power to render images; and (c) Users are relying increasingly on mobile devices that may have limited resources or capacity. As a result of these trends, high latency in rendering virtual reality displays has become a major factor limiting adoption and applications of virtual reality technology. There are no known systems that provide sufficiently low-latency rendering and display to generate highly responsive virtual reality environments given these technology constraints, including where media delivery is contemplated.